Work machines having an attached implement, such as motor graders, excavators, mining shovels, back hoe loaders, wheel loaders, track type tractors, wheeled tractors, compactors, track type loaders, and the like are used for moving earth. Such implements may include buckets, blades, impact rock rippers, and other material handling apparatus. Typically, work machines may be configured to perform various work cycles. For example, a track type loader typically has a bucket used to dig, collect (rack) a load, carry a load, and/or dump a load.
Generally, a work machine has a frame and an implement having a linkage operably connecting the implement to the frame. Typically, as the work machine performs various work cycles, various portions of the implement and linkage are operated and the work machine is propelled across the grade. Such work cycles may include digging, loading, racking, lifting, carrying, dumping, and lowering a load. Most of these functions provide a load on the engine, thereby increasing the amount of heat generated by the internal combustion system.
Internal combustion engines and associated cooling air systems tend to be relatively noisy. Governmental bodies in many countries are continuously striving to require engine and vehicle manufacturers to reduce the noise output of their products. The manufacturers themselves also desire to reduce the noise level in order to provide operators and bi-standers with a more comfortable atmosphere.
In such an endeavor, a multiplicity of schemes and constructions have been tried, some of which make significant progress in noise reduction. It is also understood in the industry that the variables in noise reduction are many and exist in many combinations. Therefore, seemingly insignificant modifications in air flow systems sometimes represent dramatic improvements in noise reduction.
Noise reduction of engine cooling air systems has been achieved in some instances by insulating the area in relatively close proximity to the fan with a sound absorbing material. This approach achieves a reduction in the noise level of the cooling air system, however, the insulation tends to retain heat which reduces the efficiency of the cooling system associated with the internal combustion engine. Further, the increased heat can degrade other insulating materials within the engine enclosure, particularly those used in electrical and electronic systems commonly utilized on today's work machines. This heat can also affect components such as alternators, starters, belts, engine mounts, dampers, microprocessors, transistors, capacitors, and resistors.
Vehicle engine noise can be effectively attenuated by ducted enclosures which provide limited air flow access via controlled, indirect, acoustically lined paths (ducts). However, with current cooling systems, increased air restriction requires higher fan speeds to deliver adequate cooling air flow. Higher fan speeds generate high fan noise which results in an unacceptably loud vehicle. Additionally, the use of ducts allows the noise generated by the engine to escape out through the ducts. Therefore, it is desirable to minimize the number of ducts and to pay particular attention to the geometry or routing of the ducts.
Other prior attempts to reduce the noise level of cooling air flow systems have been related to axial fan geometry, including blade and shroud design. These attempts have only been marginally successful as they have not reduced the amount of noise emitted to a target sound level.
It is known from U.S. Pat. No. 5,183,382 to Carroll and granted on Feb. 2, 1993 to use a rotating fan and shroud assembly to reduce noise emitted therefrom and increase cooling system efficiency. The '382 patent teaches using the rotating fan and shroud assembly in combination with a labyrinth-type seal to improve the serviceability and reduce maintenance time and cost. The '382 patent teaches the positioning of a first end of an inlet bell-mouth portion of the shroud assembly between a pair of flexible members which allows ease of servicing and prevents recirculation of cooling air.
Further, it is known from U.S. Pat. No. 5,709,175 granted on Jan. 20, 1998 to Carroll to use a radial flow fan disposed in a plenum connected to the engine enclosure and spaced from the side walls a pre-selected distance. In the '175 patent, Carroll teaches using an inlet duct in the engine enclosure to draw outside ambient air toward a radiator located within the engine enclosure. Further, the '175 patent teaches a shroud extending into the plenum to direct air flow passing through the radiator axially toward the radial flow fan and exhausting the air radially out through an opening at the top end of the plenum.
Accordingly, the art has sought an apparatus and method of cooling a work machine which: adequately cools the engine enclosure; draws sufficient ambient air across the radiator to cool the engine; reduces the noise emitted by the internal combustion system and the cooling system; insures that electrical and electronic parts, assemblies, components, and structures will not become overheated; and is more economical to manufacture and use.
The present invention is directed to overcoming one or more of the problems as set forth above.